Surge filter for pulsating gases



Feb. 6, 1940. R. LI LEADBETTER SURGE FILTER FOR PULSATING GASES 2 Sheets-Sheet 1 Filed Aug. 31, 1933 @a ww. 1 a D p n. 0 m J o W 5.1 r 1 bi: 0 o 1 b 1 o o O o xww D n a 1 Feb. 6, 1940. R. L. LEADBETTER SURGE FILTER FOR PULSATING GASES Filed Aug. 31, 1938 2 Sheets-Sheet 2 o 0 o O. o o o o o 0 x244; z. ga e 4e Z4 67;

Patented Feb. 6, 1940 PATENT O'FFICEM SURGE FILTER FOB. PULSATING GASES Ralph L. Leadbetter, Wheaten, 111., assignor, by

mesne assignments, to Burgess Battery Com- D y, Chicago, 111., a corporation of Delaware Application August 31, 1938 Serial No. 227,654

16 Claims.

This invention relates to surge filters for flowing, pulsating gases, such as the exhaust gases of internal combustion engines, or, as the terms are loosely used, to improvements in muiilers and 5 silencers for such pulsating gas systems.

This application is a continuation in part of my application Serial No. 130,283, filed March 11, 1937. Y Although the invention is useful for the prevention of noise caused by pulsating gases generally, including, for example, the intake and delivery of'air compressors, the most severe conditions are met in the prevention of noise caused by the exhaust of internal combustion engines and for this reason the invention will be illustrated and described as applied to this particular problem. a

A large variety of constructions have heretofore been employed for the attenuation of noise resulting from the operation of internal combustion engines. Whether such muillers employ baffies, resonating chambers, or equalizing or expansion chambers, an analysis of their operation discloses that their function depends entirely upon pressure fluctuations of the gas stream and thus their eflectiveness depends upon their proximity-to points of maximum pressure change in the exhaust system. Thus, a resonating chamber tuned to attenuate a particular frequency is inoperative when located at an (velocity) antinode of that particular sound wave which it is designed to attenuate. It will be seen from they following detailed description that the present invention constitutes a radical departure from muii'iers and silencers heretofore known for the reason that it operates by virtue of the inertia imparted to the gases upon being ejected from the'engine cylinder into the exhaust system. The invention operates as a velocity smoothing device m and depends upon pressure only in the remote sense that the inertia of the exhaust gases depend upon a pressure in the engine cylinder at the time the exhaust valve is opened.

The fundamentaldistinction indicated in the preceding paragraph will become more apparent as the description of the invention proceeds.

The object of this invention is to prevent noise caused by flowing, pulsating gases by means of a device that may be located with equal efiecgas stream and to reduce back pressure and eliminate so-called "period" noises.

The essential element of a mumer embodying this invention is a receptacle 'orf'smbber tube" into which the exhaust gases are projected at tiveness at any point in the conduit carrying the high velocity from the exhaust ports of the engine. Part of. the exhaust gases are conducted directly to the muiiler outlet via a substantially unrestricted passageway without entering the snubber tube. Only that portion of each pulsa- 5 tion having suflicient inertia to cause it to Jump a gap rather than deviate in its course to follow the line of least pressure resistance enters the snubber tube. The velocity ofthe gases entering the snubber tube is arrested and the gas pres- 10 sure caused thereby dissipated through perforations in the walls of the snubber tube.

Several embodiments of the invention are illustrated in the accompanying drawings in which:

Fig. 1 is a'longitudinal, sectional view of a 15' device embodying the invention;

Fig. 2, is a longitudinal, sectional view of a modified form of the device the view being taken on line 2-2 of Fig. 4;

Fig. 3 is a longitudinal, sectional view of the 20 device of Fig. 2 taken on line 3-3 of Fig. 4; Fig. 4 is a transverse, sectional view of the device shown in Figs. 2 and 3, and C Fig. 5 is a longitudinal, sectional view of a further modification of the device. 25 v The exhaust'of an internal combustion engine consists largely of a series of rapidly traveling pulses of high pressure gas known to the art as slugs. A high velocity peak, or slug, is formed each time an exhaust valve opens. Sound waves 80 are thought to be caused by high velocity impact of these slugs with the atmosphere. These are the sharp cracks characteristic of the exhaust when not properly muiiled. A low pitchedrumble is maintained between explosions. These noises may be eliminated by dissipating the velocity peaks to smooth out the flow of the gases through the exhaust system before exhausting to the atmosphere at a relatively uniform velocity. In addition to these noises, period'noises are caused at certain firing frequencies of the engine. These periods occur when the firing frequency substantially coincides with the natural resonant frequency of the exhaust system or a harmonic thereof, the timed recurrence of the pulsations tending to set the exhaust system in vibration. vPeriods may also occur "when the exhaust slugs reinforce every second, or every third,

' etc., sound wave condensation without interven- 5o ing neutralizing slugs. Resonance of the exhaust system depends-largely upon reflectionoithe atmospheric impact into the system. The device 01 this invention, which will be reierred to as a muiller for convenience; is eitective in preventing enveloping shell.

such impacts and thus in preventing both direct and period noises.

All of the mufllers are illustrated in their pre-- ferred forms, that is, contained within a single The muiiler of Fig.- l employs 'a shell III which may be circular or elliptical in cross-section, the ends being closed by flanges II p and. [2 having inlet opening l3 and outlet opening .14. respectively.- Inlet snout I5 is mounted in inlet opening. l3 and outlet snout I6 is mounted in-outlet opening l 4. These snouts are provided for convenience in mounting the mui'fler in the exhaust line. A snubber-unit is arranged within the muffler. It consists of a perforated snubber'tube I! mounted between partition [8 and end flange, l2. Partition I3 is spaced, from end flange to form a bypass chamber l9 and is provided with openings 20 and 2|, the former opening being in register-with opening 13 in flange II and the latter opening being in nonalignment with opening l3. The mouth of snubber tube I1 is mounted on partition l8 at-opening 20, the remote end of the snubber tube being closed by end flange l2. The ends of inlet snout l5 and/or snubber tube I1 may extend-into by pass chamber l9, but a gap a. must be provided between contiguous ends of these two members. this gap being not substantially less than onefourth of the diameter of snout l5. words, the cylindrical area forming the gap between the snout I5 and snubber tube 11 should not be substantially less than the cross-sectional area of the exhaust pipe of the engine. Substan tially unrestricted flow of gases through snout l5 and by-pass chamber [9 to-opening- 21 is thus provided with the result that back pressure due to restriction within themuffler is practically nil.

Perforated conduit 2 2.is mounted on partition 13 at opening 2| and on end flangel2 at opening I4. Outlet snout l6 may-be integral with conduit 22. Conduit 22 is perforated so that gases.

dissipated from snubber tube I'I through the perforations therein may pass therelnto. Space 23 operates as an expansion chamber to attenuate the high frequencysouhd waves and pulsations in conduit 22.

.The engine exhaust gases enter the muffler through snout l5 and opening l3. The inertia of theslug causes the gases forming the peakvelocity portion of the slug to Jump the gap at and project into snubber tube Il wherein the slug is cushioned and the velocity energy is transformed into static pressure which is dissipated through the perforations of the snubbertube. The snubber tube must be of suflicient volume andsufliciently perforated to accommodate the velocity peak portion of the slug but must not be so extensively perforated that the slug .will

be permitted to project through the'walls of the snubber tube without undergoingthe transformation described. The portion of the gases of thepulsation which do not have 'sufllcient inertia to a jump the gap and enter the snubber tube follow the path of less resistance and flow through bypass chamber l3 into conduit 22. A- smoothing has been accomplished by the operation of the snubbing unit Junctioning as a surge filter and the gases are collected and discharged from the relatively little sound producedybecause there is 4 inlet snout 33 are provided to conduct the pulsat- In otherduit 36 thereby enabling gases in space 38 to entransversely within the casing, being spaced from outlet conduit 53 connects byvp'ass chamber 41 lecting tubes may be .used.

" placement of 221' cubic inches, the muffler is 18 inches long and 6 inches in diameter] snubber tube I1 is 2 inches in diameter and tube 22 is also 2 inches in diameter. Partition I3 is spaced 1 inches from the end flange ll so that gap a is approximately 1 inches. Tube I1 is perforated with inch holes spaced 2 inches apart 'on centers and tube 22 is perforated with similar holes spaced 1 inch apart on centers.

T he muflier illustrated in Figs. 2, 3 and 4' is similar to that above described with the addition of a third perforated collecting tube. snubber tube 24 is mounted within shell 25 between partions 26 and-21, the latter being spaced inwardly from end flanges 28 and 23 to form by-pass chamber 30 and expansion chamber 3| at, the respective ends of the muffler. An inlet opening 32 and ing gases into the device and an outlet opening 34 and outlet snout are provided to conduct the gases from the murder. Conduit 36 is the counter part of perforated conduit 22 in the'n'miller of Fig. l and connects by-pass chamber 33 with expansion chamber 3|, the latter being connected with the exhaust outlet. This conduit is .11- lustrated as perforated but is not necessarily so since a perforated collecting tube 31 is provided to receive gases from the snubber tube 24. C01- lecting tube 31 is mounted between partitions 26 and 21 and opens into expansion chamber 3! but is closed at the other end by partition 26. This tube is perforated to a greater extent than conter the tube readily and pass into chamber 3|.

Another species ofthe invention is shown' in Fig. 5.: This device embodies a pair'of snubber units functioning independently of each other and illustrates a form which the snubber tubes may take in order to provide a muiiler which is. relatively short in the direction of gas flow. It

' may be particularly useful for the prevention of noise from twin engines or a single-engine having twin banks of cylinders. A casing 39 is provided with a pair of inlet openings 40 and 4| having inlet snouts 42 and 43 mounted therein and an outlet opening 44, through which extends the outlet snout or tail pipe 45. A partition 43 is mouhted the inlet end thereof to form .by-pass chamber 41. Perforated'snubber tubes 43 and 43 having enlarged volumes, as shown, are mounted between the outlet end portion of the casing and partition 46, opening into by-pass chamber 41. Perforated with outlet opening 44 and may be integral with outlet snout 45. p

The two modified forms of-the invention operate as above described to attenuate the velocity.- peaks of the pulsating gases conducted through them. Any desired number of snubber units may be-employed in a single device to operate independently of each other and any number of col- The devices described herein which are onl generally referred to as mui'flers and have come to be known as snubbers, may be inserted at any point of the pulsating gas system. They may be used in appropriate sizes for the muniing' of ex- 7 eluding a shell, gas-velocity-peak snubbing means acterized in that the passageway through the hausts of all types of engines, including large size Diesel engines, and also may be used inthe prevention of noises at the intake and outlet of positive displacement blowers and air compressors. Since back pressures increase with the velocity of the gases traveling through a conduit, and since the snubber tube muiller substantially reduces peak velocities, the back pressures are accordingly greatly reduced by the device.

While several specific embodiments of the invention are shown, it is obvious thatmany modiflcations may be made without departing from the spirit thereof. The snubber tubes may be designed in variousconfigurations for particular embodiments and the gap between the inlet snout and the mouth of the snubber tube may be formed by a number of large openings in acon'tinuous tube provided the totality of such openings is equivalent to a suitable gap. The lower limit of the gap has been described above, but there is no critical upper limit.

I claim: 1. In a device of the character described in within said shell and comprising means forming a chamber having an inlet ope i g and an outlet opening, conduit means arranged in said inlet opening and adapted to conduct gases into said chamber, a receptacle having apertured walls and a mouth, said mouth of saidreceptacle being in direct communication with said chamber and in alignment with said conduit means whereby gases conducted into said chamber may project into said receptacle, and means for egress of gases from said shell, said chamber outlet opening being in direct communication with said chamber inlet opening and in communication with said egress means.

2. A device in accordance with claim 1 characterized in that said receptacle is elongated in,

a direction in alignment with said conduit.

3. A device in accordance with claim 1 charconduit means, chamber, outlet opening and egress means is substantially unrestricted to the flow of gases therethrough.

4. In a device-of the character described in;

cluding a shell having means for ingress of gases thereinto and means for egress'oi' gases therefrom, gas-velocity-peak snubbing means comprising means forming a by-pass chamber having an inlet opening and an outlet opening, a conduit for conducting gases into said by-pass chamber arranged in said inlet opening and terminating within said chamber, an apertured snubber tube having a mouth opening into said chamber in alignment with saidfconduit, the end of said conduit within said chamber being spaced from said snubber tube, mouth to provide a gap through which gases from said conduit may flow directly to saidoutlet opening. g

5. A device in accordance with claim 4 in which the area of the, gap between the conduit and the subber tube mouth is not substantially less than the transverse area of said conduit.

' 6. In a device of the character described comprising a shell having an inlet opening and an outlet'opening in the respective ends thereof, a

transverse partition within said shell spaced fromthe inlet end thereof to form a by-pass chamber being in'alignment with said inlet opening and spaced irom the periphery thereon-and a per- 3 forated conduit connecting said by-pass-chamber with said outlet opening.

'1. The device of claim 6 in which the meutn chamber, snubbing means comprising a tube in substantially axial alignment with said inlet opening, the walls of said tube being perforated, the inlet end of said tube opening into said bypass chamber and theopposite end being substantially closed said partition having a vent not in alignment with saiddnlet opening, a passageway substantially unrestrictedto the flow of gases therethrough extending from said inlet opening via said vent to said outlet opening, the

degree of perforation of the walls of said tube gases entering said tube to pass through the per- Iorations, the space surrounding said tube being in communication with said unrestrited passage way.

9. A mufller comprising a shell having an inlet opening and an outlet opening, a first partition within said shell forming a by-pass chamber adjacent said inlet opening which latter opens into said by-pass chamber, -a second partition forming an expansion chamber within said shell adjacent said outlet opening which latter opens into said expansionchamber, said first and second partitions being spaced apart to form a space intermediate said chambers, a perforated tube in'substantially axial alignment with said inlet opening and opening into said by-pass chamber the opposite end being closed, said tube extending through said intermediate space to a point adjacent said expansion chamber, a tube in substantially axial alignment with said outlet opensaid expansion chamber, and aesecond perforated tube opening into said-expansion chamber and extending thorugh said intermediate space to a point adjacent said by-pass chamber, the end of said second perforated tube adjacent said by-pass chamber being closed.

10. A muiiier in accordance with claim 9 in which said tube connecting said by-pass chambeing suflicient to allow a substantial part of the a ing and connecting said by-pass chamber and ber and said expansion chamber passes through said intermediate space and is perforated.

11. In a muiller having a cylindrical shell and inleteend and outlet-end closure plates, said said inlet-end closure plate having an inlet open; ing therein and said outlet-end closure plate having an outlet opening therein, a transverse partition within said shell i'orming a by-pass chamber adjacent said inlet-end closure plate into which said inlet opening opens, a snubber tube arranged within said shell between said bypass chamber and said outlet-end closure plate opening into said by-pass chamber, the mouth portion 01' said snubber tube being in substantial alignment with said inlet opening and spaced from the contiguous peripheral portion of said inlet opening, said snubber tube having an enlarged portion at the end remote from the mouth portion thereof, said partition having a vent .not in alignment with 'saidinlet opening,

and means for connecting said vent with said .outlet opening.

12. 'l'hemuflierotclaimilinwhichsaidmeans tube opening into said by-pass chamber foreach of said inlet openings, the mouth portion 01' each 'saidsnubber tube 'being in substantial alignment withits associated inlet opening and being spaced from the contiguous peripheral portion of said associated inlet opening, and a conduit within said shell connecting said by-pass chamher with said outlet opening.

} alum 14. The device-o! claim 18in which the walls of said conduit connecting said ivy-pass chamber and said outlet opening are periorated.

15. The device of claim 13 in which said perforated snubber tubes are arranged within said shell and the walls of said conduit connecting said by pass chamber and said outlet opening are perforated whereby communication is established between the interiors oi said said conduit. p v

16. The device of claim 18 in which each of said snubber tubes has a cylindrical portion adjacent the mouth thereof' and a portion 0! enlarged cross-sectionalarea at the end remote from the mouth portion thereof.

snubber tubes and RALPH LQIEADBE'I'I'ER. 

